U.S. patent application number 15/127132 was filed with the patent office on 2017-05-04 for test unit for quantitative analysis of a contact pattern on a tooth surface of a gear, method for quantitative analysis and use of the test unit.
The applicant listed for this patent is AREVA WIND GMBH. Invention is credited to Samer Mtauweg.
Application Number | 20170122837 15/127132 |
Document ID | / |
Family ID | 50396868 |
Filed Date | 2017-05-04 |
United States Patent
Application |
20170122837 |
Kind Code |
A1 |
Mtauweg; Samer |
May 4, 2017 |
Test Unit for Quantitative Analysis of a Contact Pattern on a Tooth
Surface of a Gear, Method for Quantitative Analysis and use of the
Test Unit
Abstract
A test unit for quantitative analysis of a contact pattern and a
method for quantitative analysis are provided. The test unit
comprises an optoelectronic sensor that captures images of a
contact pattern paint on a tooth surface of a gear. Furthermore,
the test unit comprises a control unit, which is configured to
determine and store a first distribution of an optical parameter of
the contact pattern paint across the tooth surface from the first
image. This is captured prior to testing of the gear. After the
tooth surface is exposed to a test load, a second image is captured
and a second distribution of the optical parameter is determined.
The control unit is configured to perform a quantitative analysis
of a contact pattern on the tooth surface by determining a
deviation between the first and the second distribution of the
optical parameter.
Inventors: |
Mtauweg; Samer;
(Bremerhaven, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
AREVA WIND GMBH |
Bremerhaven |
|
DE |
|
|
Family ID: |
50396868 |
Appl. No.: |
15/127132 |
Filed: |
March 20, 2015 |
PCT Filed: |
March 20, 2015 |
PCT NO: |
PCT/EP2015/055895 |
371 Date: |
September 19, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01M 13/021 20130101;
F16H 2057/0087 20130101 |
International
Class: |
G01M 13/02 20060101
G01M013/02 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 20, 2014 |
EP |
14 160 930.5 |
Claims
1. A test unit for quantitative analysis of a contact pattern on a
tooth surface of a gear, in particular a test unit for a gear of a
wind generator, wherein the test unit comprises: a) an
optoelectronic sensor to capture images of a contact pattern paint
on a tooth surface of the gear, b) a control unit, which is
configured to determine and store a first distribution of an
optical parameter of the contact pattern paint across the tooth
surface from a first image, which is captured before the tooth
surface is exposed to a test load, and to determine and store a
second distribution of the optical parameter of the contact pattern
paint across the tooth surface from a second image, which is
captured after the tooth surface is exposed to the test load, and
wherein c) the control unit is further configured to perform a
quantitative analysis of a contact pattern on the tooth surface by
determining a deviation between the first and the second
distribution of the optical parameter of the contact pattern paint
across the tooth surface.
2. The test unit according to claim 1, wherein the optoelectronic
sensor is a camera which is configured to capture images of the
tooth surface.
3. The test unit according to claim 1, wherein the optoelectronic
sensor is a color sensor which is configured to capture color
images of the tooth surface, and wherein the optical parameter is a
color, a color intensity, a hue, or a brightness of the contact
pattern paint, or the optical parameter is a combination of two or
more of a color, a color intensity, a hue, or a brightness of the
contact pattern paint.
4. The test unit according to claim 1, wherein the optoelectronic
sensor is a grayscale sensor which is configured to capture
grayscale images of the tooth surface, and wherein the optical
parameter is a brightness of the contact pattern paint.
5. The test unit according to claim 1, wherein the control unit is
further configured to determine a face load distribution across the
tooth surface from the deviation between the first and the second
distribution of the optical parameter.
6. The test unit according to claim 1, wherein the control unit is
further configured to determine a face load factor of the tooth
surface from the deviation between the first and the second
distribution of the optical parameter.
7. The test unit according to claim 1, wherein the test unit is a
portable device.
8. A method for quantitative analysis of a contact pattern on a
tooth surface of a gear, in particular of a gear of a wind
generator, the method comprising the steps of; a) applying a
contact pattern paint on a tooth surface of the gear, b) capturing
a first image of the tooth surface, c) determining and storing a
first distribution of an optical parameter of the contact pattern
paint across the tooth surface; from the first image, d) performing
a test of the gear, wherein the tooth surface is exposed to a test
load, e) subsequently capturing a second image of the tooth
surface, f) determining a second distribution of the optical
parameter of the contact pattern paint across the tooth surface
from the second image, and g) performing a quantitative analysis of
a contact pattern on the tooth surface by determining a deviation
between the first and the second distribution of the optical
parameter of the contact pattern paint across the tooth
surface.
9. The method according to claim 11, wherein the step of capturing
the first or second image includes capturing of a digital image of
the tooth surface.
10. The method according to claim 11, wherein the captured image is
a color image and the optical parameter is a color, a color
intensity, a hue, or a brightness of the contact pattern paint, or
the optical parameter is a combination of two or more of a color, a
color intensity, a hue or a brightness of the contact pattern
paint.
11. The method according to claim 11, wherein the captured image is
a grayscale image and the optical parameter is a brightness of the
contact pattern paint.
12. The method according to claim 11, wherein the step of
performing the quantitative analysis further includes determining a
face load across the tooth surface from a deviation between the
first and the second distribution of the optical parameter.
13. The method according to claim 11, wherein the step of
performing the quantitative analysis further includes determining a
face load factor from the deviation between the first and the
second two-dimensional distribution of the optical parameter.
14. A portable or mobile device configured to perform a
quantitative analysis of a contact pattern on a tooth surface of a
gear, in particular of a gear of a wind generator, the device
comprising: a portable or mobile lest unit configured to a) apply a
contact pattern paint on a tooth surface of the gear, b) capture a
first image of the tooth surface, c) determine and store a first
distribution of an optical parameter of the contact pattern paint
across the tooth surface from the first image, d) perform a test of
the gear, wherein the tooth surface is exposed to a test load, e)
subsequently capture a second image of the tooth surface, f)
determine a second distribution of the optical parameter of the
contact pattern paint across the tooth surface from the second
image, and g) perform a quantitative analysis of a contact pattern
on the tooth surface by determining a deviation between the first
and the second distribution of that optical parameter of the
contact pattern paint across the tooth surface.
15. A method for using a test unit for quantitative analysis of a
contact pattern on a tooth surface of a gear of a wind generator,
the method comprising the steps of: a) using an optoelectronic
sensor to capture images of a contact pattern paint on a tooth
surface of the gear. b) using a control unit, which is configured
to determine and store a first distribution of an optical parameter
of the contact pattern paint across the tooth surface from a first
image, which is captured before the tooth surface is exposed to a
test load, and to determine and store a second distribution of the
optical parameter of the contact pattern paint across the tooth
surface from a second image, which is captured after the tooth
surface is exposed to the test load. c) farther using the control
unit to perform a quantitative analysis of a contact pattern on the
tooth surface by determining a deviation between the first and the
second distribution of the optical parameter of the contact pattern
paint across the tooth surface.
16. The test unit according to claim 2, wherein the camera is a
digital camera.
17. The test unit according to claim 3, wherein the color sensor is
a color camera.
18. The test unit according to claim 64 wherein the grayscale
sensor is a black and white camera.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is the U.S. national phase of PCT/EP
2015/055895, filed Mar. 20, 2015, claiming priority to EP 14 160
930.5, filed Mar. 20, 2014.
FIELD OF THE INVENTION
[0002] The invention relates to a test unit for quantitative
analysis of a contact pattern on a tooth surface of a gear, in
particular of a gear in a wind generator. The invention also
relates to a method for quantitative analysis of a contact pattern
on a tooth surface of a gear. Furthermore, the invention relates to
the use of the test unit for quantitative analysis of a contact
pattern on a tooth surface of a gear of a wind generator.
BACKGROUND
[0003] Generally, the tooth surfaces in gears do not contact each
other at the entire tooth flank. For determination of a contact
area between cooperating tooth surfaces, a contact pattern paint,
which is an oil-resistant colored paint, is applied on the tooth
surfaces prior to testing. The gear is subsequently exposed to a
test load. The contact pattern paint is abraded due to the applied
forces and a resulting contact pattern on the tooth flanks carrying
the partly paint are visually inspected afterwards. Typically, the
contact pattern is analyzed in a qualitative visual inspection,
which is mainly based on empirical expert knowledge.
[0004] For more precise determination of the boundaries between the
contact areas and the non-contact areas in the gear pattern, the
gear inspection system, which is disclosed in document US
2010/0158349 A1, applies a color camera. This captures images of
the tooth flanks. In the frames, the color values of pixels are
determined along a predetermined line across the tooth flank. The
color values for these pixels are plotted as a function of the
position of the pixels on the predetermined line. A gradient method
is then utilized to find points of maximum slope in the curve. The
method is based on the assumption that the boundaries of the
contact area can be identified with these points of maximum slope.
The analysis of the contact pattern is, however, restricted to a
more precise localization of the boundaries of the contact
area.
SUMMARY
[0005] It is an object of the invention to provide a test unit for
quantitative analysis of a contact pattern on a tooth surface.
Furthermore, it is an object of the invention to provide a method
for quantitative analysis of a contact pattern on a tooth surface.
It is still another object of the invention to provide an
advantageous use of the test unit.
[0006] In one aspect of the invention, a test unit for quantitative
analysis of a contact pattern on a tooth surface of a gear is
provided. The test unit is particularly suitable for inspection of
a gear in a wind generator. The test unit comprises an
optoelectronic sensor that captures images of a contact pattern
paint, which resides on a tooth surface of the gear. Furthermore,
the test unit comprises a control unit that is configured to
determine and store a first distribution of an optical parameter of
the contact pattern paint across the tooth surface. This is
performed by analyzing a first captured image. The first
distribution of the optical parameter is acquired before the tooth
surface is exposed to a test load. After the tooth surface is
exposed to the test load, a second distribution of the optical
parameter of the contact pattern paint across the tooth surface is
determined and stored by the control unit. This second distribution
is determined by analyzing a second image of the tooth surface,
which is captured after the test has been run. In addition to this,
the control unit is configured to perform a quantitative analysis
of a contact pattern. This analysis is based on a deviation between
the first and the second distribution of the optical parameter of
the contact pattern paint across the tooth surface.
[0007] In other words, the first distribution of the optical
parameter serves as a reference measurement. The second
distribution of the optical parameter is evaluated in view of this
initial reference measurement. Due to this calibration, not only a
qualitative analysis but a quantitative analysis can be performed.
The amount of abraded contact pattern paint can be quantified or at
least estimated.
[0008] The local value of the optical parameter, for example the
color intensity of the contact pattern paint, varies with the load,
which is applied on the tooth surface in the particular area. Due
to the quantitative analysis of the contact pattern paint, a load
distribution across the tooth surface can be determined.
[0009] The test unit according to aspects of the invention is
particularly advantageous for inspection of gears in wind
generators. These gears are frequently inspected in the field and
not under laboratory conditions. Under these circumstances, it is
hardly impossible to apply the contact patter paint with superb
homogeneity. On the contrary, it will be more realistic that the
contact pattern paint is applied slightly inhomogeneous, i.e. its
thickness will probably vary across the tooth surface.
[0010] Conventional test units, which inspect the contact pattern
paint only after the tooth surface was exposed to the test load,
fail to compensate for errors, which are due to initial
inhomogeneities. In particular, this applies to tests, which are
performed outside the lab.
[0011] The test unit according to aspects of the invention,
however, performs a calibrated measurement. This is not only less
prone to errors but also allows the abraded mass of contact patter
paint to be determined. This leads to a true quantitative analysis
of the contact pattern.
[0012] According to an embodiment of the invention, the
optoelectronic sensor is a camera, in particular a digital camera,
which is configured to capture images of the tooth surface. The
optoelectronic sensor can be a color sensor, in particular a color
camera. This is configured to capture color images of the tooth
surface. The acquired optical parameter can be for example: a
color, a color intensity, a hue, or a brightness of the contact
pattern paint. Furthermore, the optical parameter can be a
combination of two or more of the color, the color intensity, the
hue, or the brightness of the contact pattern paint.
[0013] Advantageously, the change of the contact pattern paint,
which is due to the test load, can be analyzed using various
parameters or even a combination of different parameters forming
the optical parameter. The load, which is applied on the tooth
surfaces, can have various effects on the individual parameters of
the contact pattern paint. For example, during a test run, the
color of the paint can change slower than its hue or the
brightness. The wide parameter space for defining the optical
parameter allows a detailed analysis. The optical parameter can be
tailored to the individual requirements of the gear and the test
run by selecting a suitable parameter of a couple of
parameters.
[0014] In an alternative embodiment of the invention, the
optoelectronic sensor is a grayscale sensor; in particular it is a
black and white camera. This is configured to capture grayscale
images of the tooth surface. In particular, the optical parameter
is a brightness of the contact pattern paint. Depending on the
particular requirements in the gear test, either a color camera or
a grayscale camera can be the best choice. For example, when the
brightness of the contact pattern paint turns out to be the best or
at least sufficient optical parameter, a black and white camera can
be superior to a color camera, because it typically offers the
better spatial resolution. Furthermore, a black and white camera
can be more economic, when compared to a color camera having
similar performance characteristics.
[0015] In particular, the test unit is a portable or mobile unit,
as for example a mobile phone or handheld portable device with an
integrated camera. This renders it particularly suitable for
in-field testing of gears in wind generators.
[0016] In another advantageous embodiment of the invention, the
control unit is further configured to determine a face load
distribution across the tooth surface. This is performed by
analyzing the deviation between the first and the second
distribution of the optical parameter across the tooth surface. The
distribution of the optical parameter can be a two-dimensional
distribution. For example, a value of the face load can be
considered being more or less proportional to a change in one or
more of the parameters. A high deviation of the color or the
brightness can for example indicate a high face load. In an ideal
situation, the relative change in color or brightness is known for
each individual pixel of the captured frames. This plurality of
relative values is determined from the comparison between the first
and the second frame. A particular value of the face load can be
calculated using the values for the change of the optical
parameter.
[0017] In another embodiment of the invention, a face load factor
can be calculated by analyzing the deviation between the first and
the second distribution of the optical parameter across the tooth
surface. The face load factor is typically defined as the local
maximum linear load divided by the average linear load across the
tooth surface. Based on the assumption that a change of the optical
parameter is at least substantially proportional to the load, the
face load factor can be calculated by determining a local maximum
change of the optical parameter and dividing this value by an
average value of the optical parameter across the tooth surface.
For restriction of the calculation to the line load, which is
considered in the face load factor, the values of the optical
parameter can be considered along a predetermined line on the tooth
surface.
[0018] In another aspect of the invention, a method for
quantitative analysis of a contact pattern on a tooth surface of a
gear is provided. The method is particularly suitable for analysis
of a contact pattern on a tooth surface of a gear of a wind
generator. Firstly, contact pattern paint is applied on a tooth
surface of the gear. Subsequently, an image of the tooth surface is
captured. In this image, a first distribution of an optical
parameter of the contact pattern paint across the tooth surface is
determined and data relative to the distribution is stored.
Subsequently, a test of the gear is performed, wherein the tooth
surface is exposed to a test load. Subsequent to the gear test, a
second image of the tooth surface is captured and a second
distribution of the optical parameter is determined. This second
distribution is also stored. A quantitative analysis of the contact
pattern is performed by analyzing a deviation between the first and
the second distribution of the optical parameter of the contact
pattern paint across the tooth surface.
[0019] In particular, the step of capturing the image includes
capturing of a digital image of the tooth surface. The captured
image can be a color image or a grayscale image. When a color image
is captured, the optical parameter can be a color, a color
intensity, a hue, or a brightness of the contact pattern paint.
However, the optical parameter can also be a combination of two or
more of the color, the color intensity, the hue, and/or the
brightness of the contact pattern paint. When a grayscale image is
captured, the optical parameter is the brightness of the contact
pattern paint.
[0020] In addition to this, the method according to aspects of the
invention can include a determination of a quantitative face load
distribution across the tooth surface. This is calculated from a
deviation between the first and the second distribution of the
optical parameter, which is in particular a two-dimensional
distribution across the tooth surface. Furthermore, a face load
factor can be determined from the deviation between the first and
the second distribution of the optical parameter.
[0021] Same or similar advantages, which have been already
mentioned with respect to the test unit apply to the method
according to aspects of the invention in a same or similar way and
are therefore not repeated.
[0022] In still another aspect of the invention, a use of the test
unit for quantitative analysis of a contact pattern on a tooth
surface of a gear of a wind generator is provided. Due to the fact,
the test unit performs a calibrated measurement; it is particularly
suitable for performing tests in wind generator. The test is
typically not conducted in a lab environment and the test unit can
in particular compensate for inhomogeneities of the applied contact
pattern paint. Further advantages of the use of the test unit ensue
from the description of the test unit and shall not be
repeated.
[0023] The aspects, embodiments and/or method steps of the
invention can advantageously be implemented in the form of a
computer program stored on a mobile device. The invention therefore
also provides a computer program product implementing the aspects
and features of the invention. Such a computer program is usually
referred to as an application (short: "app"). The respective app
may be downloaded and stored on a mobile and/or portable device.
The portable device may then be configured by the app in order to
perform the above described aspects and embodiments of the
invention. This is particularly advantageous for in-field
testing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Further features and advantages of the invention will become
apparent from the following description and from the accompanying
drawings to which reference is made. In the drawings:
[0025] FIG. 1 is a simplified drawing showing a test unit according
to an embodiment of the invention, and
[0026] FIG. 2 is a flow chart illustrating a quantitative analysis
of the contact pattern paint on a tooth surface, according to
another embodiment of the invention.
DETAILED DESCRIPTION
[0027] In the simplified drawing of FIG. 1, there is a test unit 2
for quantitative analysis of a contact pattern on a tooth surface 4
of a gear 6. Merely for simplification of the drawing, only a
section of the gear 6 is depicted in FIG. 1. In particular, the
gear 6 forms part of a wind generator.
[0028] The test unit 2 comprises an optoelectronic sensor 8 that
captures images of a contact pattern paint, which is applied on the
tooth surfaces 4. In particular, the optoelectronic sensor 8 is a
camera, for example a digital camera, which is configured to
capture digital images of the tooth surface 4. The optoelectronic
sensor 8 can be either a color sensor or a grayscale sensor. For
example, a digital color camera or a black and white camera, which
is either configured to capture digital color images or digital
grayscale images of the tooth surface 4, respectively, can be
applied.
[0029] The optoelectronic sensor 8 is coupled to a control unit 10
via a data link 12. Both, the control unit 10 and the data link 12
can be configured according to commonly applied technical standard
technology, which fits best with the requirements of the test unit
2. For example, the control unit 10 can be a computer, a
microcontroller or the like. The data link is a USB or FireWire
link, for example.
[0030] In particular, the test unit 2 is a portable unit. For in
the field testing of gears, for example a gear, which is installed
in a wind generator, a portable unit fits best with the needs of
the service technicians.
[0031] The analysis of the contact pattern starts with the
application of a contact pattern paint on the tooth surfaces 4.
This is performed prior to the test run of the gear 6. The contact
pattern paint is typically an oil-resistant deeply colored paint.
Conventional contact pattern paints can be applied for testing of
the gear 6.
[0032] However, before the test run is performed and the tooth
surfaces 4 of the gear 6 are exposed to the test load, a first
image of the tooth surface 4 is captured using the optoelectronic
sensor 8. The image data is communicated via the data link 12 from
the optoelectronic sensor 8 to the control unit 10.
[0033] The control unit 10 is configured to analyze the image data
of the captured image. This analysis can be performed with respect
to various optical parameters of the contact pattern paint.
Suitable optical parameters are for example: the color, the color
intensity, the hue, or the brightness. Naturally, this requires a
color sensor. Furthermore, the optical parameter can be a
combination of two or more of the named parameters. In other words,
the optical parameter can be a combination of two or more of the
color, the color intensity, the hue, and/or the brightness of the
contact pattern paint. When a grayscale sensor is applied, the
optical parameter is likely to be the brightness of the contact
pattern paint.
[0034] The control unit 10 determines a first distribution of the
optical parameter of the contact pattern paint across the tooth
surface 4. When the optical parameter is, for example, the
brightness, a two-dimensional distribution of the brightness of the
contact pattern paint across the tooth surface 4 is determined.
This can be performed on a pixel-by-pixel basis. In other words,
the control unit 10 stores a value of the brightness for each pixel
in the captured frame. Each pixel can be assigned to a certain
point or a tiny area on the surface 4 of the tooth. In other words,
each pixel represents information with respect to a location on the
tooth surface 4. The location of an individual pixel together with
its brightness value represents one single coordinate in the
two-dimensional distribution of the optical parameter. The entirety
of locations of the pixels in a single frame together with
brightness values, represent one possible two-dimensional
distribution of the optical parameter. In a similar way, various
other distributions of the optical parameter across the tooth
surface 4 can be generated using one or more of the named
parameters, for example the hue and/or the color intensity.
[0035] Subsequent to the acquisition and analysis of the first
image, a test run is performed. The tooth surface 4 of the gear 6
is exposed to a test load. Subsequent to testing, a second image is
captured using the optoelectronic sensor 8.
[0036] This second image provides the data basis for a similar
analysis, which was carried out prior to testing. This reveals in a
second distribution of the optical parameter, which is also stored
in the control unit 10. In contrast to the first image, the second
image includes data of partially abraded contact pattern paint.
This is due to the load, which was applied in the test run.
[0037] The first distribution of the optical parameter, which
characterizes the contact pattern paint prior to testing, and the
second distribution of the optical parameter, which characterizes
the contact pattern paint after testing, are now available. The
control unit 10 calculates a deviation between the first and the
second distribution of the optical parameter. Again, this can be
performed on a pixel-by-pixel basis. For example, the values for
the brightness of corresponding pixels in the first and second
frame can be subtracted. In other words, a brightness difference
image is determined by subtracting the brightness values of pixels
having the same location.
[0038] This differential picture provides a basis for quantitative
analysis of the contact pattern paint, in particular for
determination of a quantitative load distribution across the tooth
surface 4. In other words, the control unit 10 is configured to
determine a quantitative load distribution across the tooth surface
4 from a deviation between the first and the second distribution of
the optical parameter. Furthermore, a face load factor can be
determined. The calculation of the face load factor will be
explained in more detail below.
[0039] The above outlined mode of operation of the control unit is
advantageously applicable to various optical parameters. For
example, the optical parameter can be the color, the color
intensity, or the hue of the contact pattern paint. Also a
combination of two or more parameters can serve as the optical
parameter. If more than one parameter provides the basis for the
optical parameter, the individual parameters forming said optical
parameter can also be weighted. The choice of the suitable
parameters depends on the particular requirements and circumstances
of the gear test. The combination and the weight of the parameters
can be tailored to the particular requirements. As already
mentioned, the optical sensor 8 can be a color sensor or a
grayscale sensor. When the brightness of the contact pattern paint,
for example, turns out to be the suitable optical parameter for
characterizing the abrasion of the contact pattern paint, a black
and white camera will be sufficient. In comparison to a color
camera, a black and white camera typically offers the higher
spatial resolution. This can be advantageous for some
applications.
[0040] The test unit 10 according to aspects of the invention is
capable of determining an amount of contact pattern paint, which is
abraded from the tooth surface 4 during the test run. This is no
self-evident feature since the initial distribution of the contact
pattern paint is not necessarily homogeneous. Only by performing a
reference measurement, i.e. the first distribution of the optical
parameter, can the analysis be a quantitative analysis. This is not
based on absolute values but on calibrated values of the optical
parameter. With this type of measurement, the influence on the
contact pattern paint, which is due to testing, can be filtered
out.
[0041] The calibrated measurement enables the control unit 10 to
perform a quantitative analysis. Based on the assumption that a
load on a particular area on the tooth surface 4 is substantially
proportional to a change in one or more of the optical parameters
of the contact pattern paint in said area, the load distribution
across the tooth surface 4 can be determined. When a certain area
of the tooth surface 4 is subject to a high load, the contact
pattern paint is expected to be heavily abraded. This will
significantly change the optical parameter in this particular area.
In other words, areas showing a high change in brightness, for
example, are assumed to be exposed to a high load.
[0042] Based on information with respect to a difference between
the first and second distribution of the optical parameter, a face
load factor can be calculated. Generally, the face load factor is
defined as:
K H .beta. = ( Fm / b ) ma x Fm / b , ##EQU00001##
wherein Fm/b is the average linear load across the tooth surface
and (Fm/b)max .quadrature. is a local maximum linear load.
[0043] The face load factor is dimensionless. It is calculated from
the relation between the average linear load and the local maximum
linear load. Starting with the above-mentioned assumption that the
load is more or less proportional to a change in the optical
parameter, the color or brightness values, for example, will equal
the local load on the tooth surface 4 multiplied by a scale factor.
By analyzing the optical parameter along a predetermined line
across the tooth surface 4, a value, which is proportional to the
average linear load along this particular line, can be calculated.
Similarly, the value of the local maximum linear load (multiplied
by the identical scale factor) can be determined from the deviation
of the optical parameter. When the face load factor is determined
using the above formula, the scale factors cancel out.
[0044] In FIG. 2, there is a flow chart illustrating a method for
quantitative analysis of a contact pattern on a tooth surface in a
gear 6, according to an embodiment of the invention.
[0045] The method starts (step S0) with the application of contact
pattern paint on the tooth flanks or tooth surfaces 4 of the gear 6
(step S1). A first image of the tooth surface 4 is subsequently
captured (step S2). The image data is communicated from the
optoelectronic sensor 8 via the data link 12 to the control unit
10. A first two-dimensional distribution of an optical parameter,
for example the brightness or the color of the contact pattern
paint, is determined (step S3). This first distribution of the
optical parameter is stored (step S4). Subsequently, a test run is
performed. The tooth surfaces 4 of the gear 6 are exposed to a test
load (step S5). After the test run, a second image of the tooth
surface 4 is captured using the optoelectronic sensor 8 (step S6).
The image data is again communicated via the data link 12 to the
control unit 10. A second two-dimensional distribution of the
optical parameter is determined (step S7). This is stored in the
control unit 10 (step S8). Subsequently, the first and the second
distribution of the optical parameter, which characterize the
contact pattern paint prior and after testing, are compared (step
S9). The deviation between the first and second two-dimensional
distribution of the optical parameter, provides a basis for a
quantitative analysis of the contact pattern (step S10). For
example, a load distribution across the tooth surface 4 or a face
load factor can be calculated (step S10). If no further measurement
is desired, the method stops in step S11.
[0046] Although the invention has been described hereinabove with
reference to specific embodiments, it is not limited to these
embodiments and no doubt further alternatives will occur to the
skilled person that lie within the scope of the invention as
claimed.
* * * * *